MYOCARDIAL INFARCT IMAGING AFTER CARDIAC SURGERY*

One hundred and nineteen patients undergoing cardiac surgery had postoperative myocardial imaging performed with technetium pyrophosphate in order to assess the incidence of perioperative myocardial infarction. Fifty-six patients had only coronary artery bypass graft (CABG) surgery, of whom 13 (23%) had a positive scintigram. Thirteen patients had CABG with other cardiac surgery and six (46%) had a positive scintigram. Fifty patients had other cardiac surgery but no CABG, and of these eight (16%) had a positive scintigram. The overall incidence of positive scintigrams was 23%, whereas definite or probable ECG diagnosis of infarction was present in 14 patients (12%). Serum levels of cardiac enzymes were higher in patients with positive scintigrams, but this finding did not consistently reach statistical significance. The use of a left ventricular vent during surgery did not correlate with a positive scintigram, nor did the total time on cardiopulmonary bypass or aortic cross-clamping. Patients having cardiac surgery, including CABG and valve replacement, have a 23% overall incidence of positive scintigrams. This suggests that the incidence of infarction after cardiac surgery is higher than can be recognized from the conventional criteria of ECG and enzyme changes.     

Preoperative and postoperative technetium-99m pyrophosphate myocardial scintigraphy in the assessment of operative infarction in coronary artery surgery.

The incidence of operative myocardial infarction was assessed by electrocardiogram (ECG) and technetium-99m pyrophosphate (99mTc-PyP) myocardial scintigrams in 89 consecutive patients undergoing coronary artery bypass grafting (CABG). Myocardial scintigrams were performed on the day before operation and repeated 2 to 3 days postoperatively. All patients survived operation, with three in-hospital deaths not related to myocardial infarction (mortality rate 3 percent). Operative infarction was assessed to have occurred in four of 89 patients (4 percent). Two had new Q waves and positive scintigrams; one, major ST-T wave changes and a positive scintigram; and the fourth, new Q waves without a positive scintigram. Three further patients (3 percent) had Q waves and positive scintigrams postoperatively, but myocardial infarction was evolving before anesthesia and operation. Twenty-seven of 89 patients (30 percent) were found to have abnormal scintigrams preoperatively. In two patients, both operated upon with evolving myocardial infarction, the scintigram was worse postoperatively. In 13 patients the scintigram was improved after operation. In 12 patients (13 percent) the abnormal preoperative scintigram was unchanged after operation. Preoperative and postoperative myocardial scintigrams and ECG's must be compared to assess the incidence of operative myocardial infarction in patients undergoing CABG.     

Perioperative myocardial ischemia in patients undergoing sternectomy shortly after coronary artery bypass grafting

Coronary revascularization reduces cardiac complications associated with noncardiac surgery in patients with severe coronary disease. However, patients undergoing emergency noncardiac surgery soon after coronary bypass operations may still be vulnerable to ischemic myocardial events. We prospectively evaluated the incidence of myocardial ischemia in 82 consecutive patents scheduled for sternectomy in the first (Group 1; 35 patients) or second (Group 2; 47 patients) week after coronary artery bypass graft (CABG) surgery. The interval between CABG surgery and sternectomy in Groups 1 and 2 was 6 days (range, 4-7 days) and 11 days (range, 8-14 days), respectively. Electrocardiographic (ECG) changes consistent with myocardial ischemia were assessed with a two-channel Holter system for 48 h. There were no between-group differences in updated Acute Physiology and Chronic Health Evaluation score, use of beta-blockers, or perioperative hemodynamic changes. The incidence of ECG changes consistent with myocardial ischemia was fivefold more frequent in Group 1 (22.85% versus 4.25%; P < 0.05). Of the ischemic patients in Group 1, 25% experienced a perioperative acute myocardial infarction (one was fatal). There were no infarcts in Group 2. Thus, patients appear to be prone to coronary events during sternectomy performed early after CABG surgery. Although the incidence of ischemia did not differ from that previously reported after CABG surgery alone, further investigation is required to determine whether the findings obtained in this high-risk population are generalizable to patients undergoing noncardiac surgery soon after uneventful CABG surgery. IMPLICATIONS: This study demonstrates an increased incidence of myocardial ischemia when sternectomy for mediastinitis is performed within one week of coronary artery bypass graft surgery, and this ischemia is associated with a 25% incidence of myocardial infarction.     

The Concordance of Intraoperative Left Ventricular Wall-motion Abnormalities and Electrocardiographic S-T Segment Changes: Association with Outcome after Coronary Revascularization

Background: Transesophageal echocardiography (TEE) and Holter electrocardiography (ECG) are used to detect intraoperative ischemia during coronary artery bypass graft surgery (CABG). Concordance of these modalities and sensitivity as indicators of adverse perioperative cardiac outcomes are poorly defined. The authors tried to determine whether routine use of Holter ECG and TEE in patients with CABGs has clinical value in identifying those patients in whom myocardial infarction (MI) is likely to develop.

Methods: A total of 351 patients with CABG and both ECG-and TEE-evaluable data were examined for the occurrence of ischemia and infarction. The TEE and five-lead Holter ECGs were performed continuously during cardiac surgery. The incidence of MI (creatine kinase-MB >or= to 100 ng/ml) within 12 h of arrival in the intensive care [ICU] unit, new ECG Q wave on ICU admission or on the morning of postoperative day 1, or both, were recorded.

Results: Electrocardiographic or TEE evidence of intraoperative ischemia was present in 126 (36%) patients. The concordance between modalities was poor (positive concordance = 17%; Kappa statistic = 0.13). Myocardial infarction occurred in 62 (17%) patients, and 32 (52%) of them had previous intraoperative ischemia. Of these, 28 (88%) were identified by TEE, whereas 13 (41%) were identified by ECG. Prediction of MI was greater for TEE compared with ECG.     

Atrial fibrillation after coronary artery bypass grafting without cardiopulmonary bypass.

OBJECTIVE: Atrial fibrillation is the most common complication after heart surgery. It rarely has a fatal outcome but causes patient instability, prolongs hospital stay, or even is the reason for perioperative infarction. Although conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass has excellent short-term and long-term results, the number of coronary operations on a beating heart without cardiopulmonary bypass is still growing. To reduce surgical trauma, off-pump coronary artery bypass grafting via sternotomy (OPCABG) or minimally invasive direct vision coronary artery bypass grafting (MIDCABG) via small thoracotomy are performed. The aim of this study was to estimate the frequency of atrial fibrillation in patients after myocardial revascularization without cardiopulmonary bypass. METHODS: A retrospective analysis of 48 patients undergoing myocardial revascularization without cardiopulmonary bypass was performed. Twenty-four patients underwent OPCABG and 24 were operated using the MIDCABG technique. The incidence of cardiac arrhythmias was analyzed since operation to the fourth postoperative day. Each patient had continuous ECG monitoring with option of arrhythmia analysis during ICU stay. After discharge from ICU 24-h ECG monitor studies were carried out. Surface 12-lead ECG was accomplished once a day, and additionally each time symptoms of cardiac arrhythmia occurred. Risk factors of atrial fibrillation were estimated. RESULTS: Atrial fibrillation occurred in 25% of patients after MIDCABG, in 29% after OPCABG, and in 18% after CABG with cardiopulmonary bypass. This difference has no statistical significance. Risk factors and incidence of postoperative complications were comparable in all groups. CONCLUSIONS: Atrial fibrillation is a common complication after procedures of myocardial revascularization, performed with or without cardiopulmonary bypass. The occurrence is not dependent on the type of operation.     

ECG changes after CABG: the role of the surgical technique

OBJECTIVE: The purpose of this study was to determine whether coronary artery bypass grafting (CABG) surgery on the beating heart (BH) is associated with reduction of R-wave potentials on the precordial leads on the surface electrocardiogram (ECG) as previously shown for CABG with cardiopulmonary bypass. METHODS: Fifty-four patients undergoing CABG surgery at a single tertiary care university hospital were analyzed. Patients suffering a postoperative cardiac event (myocardial infarction) or nonspecific ECG changes were excluded. ECG results were recorded at arrival in the intensive care unit, after 4 and 18 hours postoperatively; simultaneously, myocardial cell damage biomarkers (CK-MB and cTnI) were assayed. A control group of 31 patients undergoing mitral valve repair was also evaluated. RESULTS: Patients operated with the BH (OPCABG) technique did not show any decrease of R-wave amplitude at 0, 4, and 18 hours postoperatively; whereas those operated with CPB, both for coronary artery surgery and for mitral repair, had a similar extent and pattern of R-wave reduction. The release of myocardial necrosis markers was significantly lower in coronary artery patients operated with BH than in those operated with CPB; however, no statistically significant correlation between the ECG changes and release of myocardial cell damage markers was observed in any of the groups. CONCLUSIONS: The findings indicate, for the first time, that CABG surgery on the BH is not followed by any reduction of R-wave amplitude on precordial leads and confirms that the BH technique is associated with a lower release of myocardial cell damage markers.     

Scintigraphic demonstration of myocardial perfusion and ischaemia associated with coronary artery bypass grafting

OBJECTIVES: To assess if myocardial perfusion scintigraphy (MPS) at rest can be of value in elucidating myocardial perfusion, ischaemia and perioperative myocardial infarction (PMI) associated with coronary artery bypass graft (CABG) surgery. DESIGN: This was a prospective randomized study of patients undergoing elective CABG. Forty-eight patients in the control group underwent serial ECG recordings and measurements of CK-MB and cTnT. Fifty-four patients in the study group were additionally examined with MPS preoperatively and 2-4 days and 6 weeks postoperatively. RESULTS: The study showed a highly significant (p < 0.001) improvement in myocardial radionuclide uptake from preoperatively to 2-4 days postoperatively. Judged from ECG and enzymatic changes, two control patients and one study patient only had PMI and no additional cases of PMI were demonstrated by MPS. CONCLUSION: MPS at rest showed that CABG significantly improved myocardial perfusion, by demonstrating an increase in radionuclide uptake. In diagnosing PMI, we found that MPS provided no additional information beyond cardiac biochemical markers and ECG changes.     

Timing of high-risk vascular surgery following coronary artery bypass surgery: a 10-year experience from an academic medical centre

Major non-cardiac surgery within 40 days of coronary angioplasty with stenting has high cardiac complication rates. We have performed a case-control study to determine whether the risk of vascular surgery might have increased in recent survivors of coronary artery bypass surgery (CABG). Using our vascular database from 1990 to 1999, we matched the cases who had vascular surgery within a month of CABG with controls by pre-operative comorbidities of diabetes mellitus, history of myocardial infarction (MI), history of congestive heart failure (CHF), and chronic renal insufficiency and compared the incidence of peri-operative MI, CHF, death, and other complications. Compared to case-matched controls, patients who underwent vascular surgery within a month of CABG suffered significantly greater mortality (20.6% vs. 3.9%, p < 0.005). The incidence of non-fatal cardiac complications was not significantly different between the groups. We conclude that the risk of mortality may be significantly greater in patients undergoing major vascular surgery within a month of CABG.     

The influence of propofol versus sevoflurane anesthesia on outcome in 10,535 cardiac surgical procedures

OBJECTIVE: The purpose of this study was to evaluate the possible cardioprotective effect of sevoflurane versus propofol anesthesia in patients undergoing cardiac surgery. METHODS: Ten thousand five hundred thirty-five consecutive single cardiac surgical procedures from 3 cardiac centers were reported to a common registry from 1999 to 2005. The registry was established by the National Board of Health, and reporting was obligatory for all public heart centers in Denmark. The patients were stratified according to preoperative risk factors (EuroSCORE parameters). The outcome parameters were 30-day mortality, the incidence of postoperative myocardial infarction, and the incidence of postoperative arrhythmias. RESULTS: Overall, the 30-day mortality was lower after sevoflurane (2.84%) versus propofol (3.30%), although not significantly so (p = 0.18). No difference was found in the incidence of postoperative myocardial infarction (sevoflurane, 7.76%/propofol, 7.47%). Patients with preoperative unstable angina and/or recent myocardial infarction, and thus already "preconditioned," did not show any difference in mortality between anesthetic groups, whereas patients without these predictors showed a lower postoperative mortality after sevoflurane (2.28% v 3.14%, p = 0.015), which can at least partly be explained by a preconditioning-like effect. The data suggest that patients suffering relatively severe preoperative ischemic stress benefited from propofol anesthesia, which can be related to the antioxidant effects of propofol. Patients in the sevoflurane group had a higher incidence of postoperative atrial fibrillation (28.75% v 24.87%, p < 0.001), whereas patients in the propofol group showed a higher incidence of all other arrhythmias. CONCLUSION: Sevoflurane and propofol both possess some, although different, cardioprotective properties. Sevoflurane appears to be superior to propofol in patients with little or no ischemic heart disease, such as noncoronary artery bypass graft (CABG) surgery and CABG surgery without severe preoperative ischemia, whereas propofol seems superior in patients with severe ischemia, cardiovascular instability, or in acute/urgent surgery.     

Postoperative myocardial ischemia in patients undergoing coronary artery bypass graft surgery. S.P.I. Research Group

Cardiac morbidity and mortality after coronary artery bypass graft (CABG) surgery continue to be significant problems. To determine the prevalence, characteristics, and prognostic importance of postoperative myocardial ischemia after CABG surgery, the authors monitored 50 patients continuously for 10 perioperative days with the use of two-lead electrocardiography (ECG). ECG changes consistent with ischemia were defined as a reversible ST depression of 1 mm or greater or an elevation of 2 mm or greater from baseline, lasting at least 1 min. Baseline was adjusted for positional changes and temporal drift. All episodes were verified, with the use of the ECG monitor printout (ECG complexes), by two independent blinded investigators. Clinical care was not controlled by study protocol, and clinicians were unaware of the research data collected. Twenty-six of 50 patients (52%) had 207 episodes of perioperative ischemia (3,409 ischemic minutes). Postoperatively, ischemia developed in 48% of patients, compared with 12% preoperatively and 10% intraoperatively before bypass. Postoperative ischemia was most common in the early period (postoperative days [PODs] 0-2; 38% of patients), peaking during the first 2 h after revascularization, and less common during the late postoperative period (PODs 3-7; 24% of patients). Almost all (120 of 122; 98%) postoperative episodes (after tracheal extubation) were asymptomatic: only 9 of 70 (13%) early episodes were detected by clinical ECG monitoring. Postoperative ischemia did not appear to be related to acute changes in myocardial oxygen demand: only 39% of the postoperative episodes were preceded by a greater than 20% increase in heart rate. However, tachycardia persisted throughout the postoperative week (22-33% of all heart rates greater than 100 beats per min), and patients with postoperative ischemia (POD 0) more frequently had tachycardia (median 43% vs. 12% of the time; P less than 0.01). Five adverse cardiac outcomes occurred on the day of surgery; all five were preceded by postoperative ischemia, three by intraoperative ischemia before bypass, and none by preoperative ischemia. Patients with late postoperative ischemia did not have an adverse cardiac outcome. The authors conclude the following: 1) ischemia is more prevalent postoperatively than preoperatively or intraoperatively before bypass; 2) the incidence of postoperative ischemia peaks shortly after revascularization, during which time it is symptomatically silent, difficult to detect, and related to adverse cardiac outcome; 3) late postoperative ischemia also is silent, but it is less prevalent and not associated with in-hospital adverse cardiac outcome; and 4) a relationship between ischemia and persistently elevated postoperative heart rate may exist and warrants additional investigation.     

Automated, continuous ST segment analysis in the ECG as a monitor of myocardial ischemia during aortocoronary bypass surgery

Patients with coronary artery disease (CAD) who are subjected to cardiac and major noncardiac surgical procedures have a high incidence of perioperative myocardial ischemia. Earlier studies in patients undergoing coronary artery bypass graft surgery (CABG) indicated the frequency of postoperative myocardial infarction to be directly proportional to the incidence and severity of pre-bypass myocardial ischemia. METHODS. We investigated the incidence of pre-bypass ischemia in 50 patients undergoing elective CABG using an automated ST segment monitoring system (Marquette 7010). Analyzing leads I, II, and V5, this device measures ST segment deviations 60 ms after the J-point. Occurrence of myocardial ischemia was defined as follows: new ST segment deviations larger than 1 mm = 0.1 mV that lasted for more than at least 10 consecutive heartbeats. RESULTS. In 19 out of 50 patients (38%) we found 96 episodes of myocardial ischemia in the pre-bypass period; 47% of all ischemic episodes were associated with significant hemodynamic changes, e.g., tachycardia, hypertension, or hypotension. The incidence of ischemia was different between population sub-groups: patients with a previous infarction had a lower incidence of ischemia (35%) than patients without infarction (44%). Patients with preoperative left ventricular end diastolic pressure (LVEDP) less than 15 mm Hg had a lower incidence of ischemia (29%) than patients with LVEDP greater than 15 mm Hg (50%). Patients treated preoperatively with beta-blockers showed a significantly lower incidence of ischemia (9%) when compared to untreated patients (46%, p less than 0.05). No difference was found between patients with or without unstable angina pectoris or between patients of NYHA classes II, III, or IV. Postoperative myocardial infarction occurred in 2 patients, both with evidence of pre-bypass myocardial ischemia. CONCLUSION. Our study confirms that automated ST segment analysis is able to detect myocardial ischemia similarly to that documented in previous studies using conventional ECG lead analysis.     

Scintigraphic demonstration of myocardial perfusion and ischaemia associated with coronary artery bypass grafting

Objectives. To assess if myocardial perfusion scintigraphy (MPS) at rest can be of value in elucidating myocardial perfusion, ischaemia and perioperative myocardial infarction (PMI) associated with coronary artery bypass graft (CABG) surgery. Design. This was a prospective randomized study of patients undergoing elective CABG. Forty-eight patients in the control group underwent serial ECG recordings and measurements of CK-MB and cTnT. Fifty-four patients in the study group were additionally examined with MPS preoperatively and 2–4 days and 6 weeks postoperatively. Results. The study showed a highly significant (p?<?0.001) improvement in myocardial radionuclide uptake from preoperatively to 2–4 days postoperatively. Judged from ECG and enzymatic changes, two control patients and one study patient only had PMI and no additional cases of PMI were demonstrated by MPS. Conclusion. MPS at rest showed that CABG significantly improved myocardial perfusion, by demonstrating an increase in radionuclide uptake. In diagnosing PMI, we found that MPS provided no additional information beyond cardiac biochemical markers and ECG changes.     

Early results of mitral valve replacement.

Early results of mitral valve replacement were reviewed in 336 unselected patients, 261 without and 75 with concomitant coronary artery bypass grafting (MVR and MVR + CABG groups). Early (less than 30 days) mortality was 7% in the MVR and 16% in the MVR + CABG group, with cardiac failure as the dominant cause. In multivariate analysis, the variables most strongly related to early mortality were congestive heart failure, diabetes and previous cardiac surgery in the MVR group and congestive heart failure in MVR + CABG. In the cases with fatal outcome the incidence of peroperative technical complications was 32% at MVR and 17% at MVR + CABG. The incidence of myocardial injury was 21% and 35% in the respective groups, and the early mortality in these cases was 19% vs 23%. Half of all fatal cases showed signs of peroperative myocardial injury. Multivariate analysis showed factors independently related to myocardial injury to be year of surgery and aortic cross-clamp time in MVR and previous cardiac surgery in MVR + CABG. Operation before cardiac reserves are reduced, optimal peroperative myocardial preservation and avoidance of technical errors should improve results of MVR.     

Dipyridamole thallium scanning in the evaluation of coronary artery disease in elective abdominal aortic surgery.

Dipyridamole thallium scanning was routinely performed on 68 consecutive patients who presented for elective aortic surgery. All 68 patients were judged by clinical assessment to be at low risk for perioperative cardiac complications. In addition, 42 of 68 patients had a history of myocardial infarction, stable angina, or abnormal echocardiographic findings (group 1). Twenty-six of 68 patients did not have a history of myocardial infarction, angina, or abnormal echocardiographic findings (group 2). In group 1, 34 of 4 patients had positive results on dipyridamole thallium scanning, and 15 of these patients were found to have critical coronary artery disease on subsequent cardiac catheterization; nine underwent immediate coronary artery bypass grafting, and six had their coronary artery disease treated medically and their vascular operations cancelled. The remaining 27 patients in group 1 underwent elective operations, with six (22%) of 27 sustaining postoperative cardiac complications. None of the group 2 patients was found to have critical coronary artery disease. All patients in group 2 underwent aortic operation without cardiac complication. Routine dipyridamole thallium scanning detected a 22% (15 of 68) incidence of critical coronary artery disease overall. There was a 36% (15 of 42) incidence of critical coronary artery disease in group 1 patients vs 0% in group 2 patients (95% confidence interval, 21% to 50%). We conclude that the use of dipyridamole thallium scanning in low-risk patients for cardiac screening prior to elective aortic operations is beneficial in selected patients who have a history of myocardial infarction, angina, or abnormal echocardiographic findings, but is not necessary in patients with no history of coronary artery disease.     

Determinants of myocardial infarction following emergency coronary artery bypass for failed percutaneous coronary angioplasty

Acute myocardial ischemia during percutaneous transluminal coronary angioplasty (PTCA) often necessitates emergency coronary artery bypass grafting (CABG) and can result in myocardial infarction (MI). This study was undertaken to determine what factors might predispose to MI following emergency CABG for failed PTCA. Since 1980, 24 patients at Boston University Medical Center have undergone emergency CABG following failed PTCA. In 15 patients (63%), there was postoperative evidence of an MI shown by either ECG or enzyme criteria. Variables that predisposed to a perioperative MI (p less than 0.05) included multivessel PTCA, the presence of multiple vessels with 50% stenosis or more, multivessel CABG, and the presence of new ECG changes immediately following failed PTCA. Variables that did not discriminate between the two groups included age, sex, the specific vessel involved during PTCA, or a previous history of MI. The presence of coronary collaterals did not decrease the incidence of MI. This study suggests that patients with multiple major coronary stenoses in whom acute ECG changes develop following failed PTCA are more likely to sustain a perioperative MI following emergency CABG.     

Prognostic importance of postbypass regional wall-motion abnormalities in patients undergoing coronary artery bypass graft surgery. SPI Research Group

Regional wall motion abnormalities (RWMA) detected by intraoperative transesophageal echocardiography (TEE) are thought to be sensitive markers of myocardial ischemia. To assess the prognostic significance of RWMA as compared with other less costly technologies such as electrocardiography (ECG) and hemodynamic measurements [blood pressure (BP) and pulmonary artery (PA) pressure], 50 patients were prospectively studied who were undergoing elective coronary artery bypass graft (CABG) surgery using continuous TEE, ECG (Holter), and hemodynamic measurements during the prebypass, postbypass, and early postoperative intensive care unit (ICU) periods (first 4 h). Echocardiographic and ECG evidence of ischemia was characterized during each of these three periods and related to adverse clinical outcomes (postoperative myocardial infarction, ventricular failure, and cardiac death). Clinicians were blinded to the TEE and ECG information. The prevalence of myocardial ischemia during the perioperative periods was as follows: prebypass, 20% (TEE) versus 7% (ECG); postbypass, 36% (TEE) versus 25% (ECG); ICU 25% (TEE) versus 16% (ECG). Neither prebypass TEE ischemia nor ECG ischemia occurring in any of the three periods predicted adverse outcome. In contrast, postbypass TEE ischemia was predictive of outcome: six of 18 patients with postbypass TEE ischemia had adverse outcomes versus 0 of 32 without TEE ischemia (P = 0.001). Seventy-three percent of the echocardiographic ischemic episodes occurred without acute change (+/- 20% of control) in heart rate, BP, or PA pressure. The authors conclude that: 1) prebypass myocardial ischemia was relatively uncommon, 2) the incidence of ECG and TEE ischemia was highest in the postbypass period, and 3) postbypass RWMA were related to adverse clinical outcome.     

七氟醚和异丙酚对冠状动脉旁路移植术患者心肌保护作用比较的Meta分析

目的 采用Meta分析法比较七氟醚和异丙酚对冠状动脉旁路移植术患者心肌的保护作用.方法 通过电子数据库检索比较冠状动脉旁路移植术患者七氟醚和异丙酚心肌保护作用的临床随机对照研究,文献检索至2008年9月.由两位作者分别对研究质量进行评估,并提取有关资料,主要包括患者术前情况、术中情况、体外循环后心脏指数、术后心肌肌钙蛋白Ⅰ水平、机械通气时间、正性肌力药物使用情况、ICU停留时间、住院时间、术后死亡、心肌梗死、心肌缺血和房颤的发生情况,采用RevMan 5.0软件进行Meta分析.结果 共纳入13项前瞻性临床随机对照研究,包括696例患者,其中七氟醚组402例,异丙酚组294例.两组患者术后机械通气时间、正性肌力药物使用率、术后病死率、心肌梗死和房颤的发生率差异无统计学意义(P>0.05).与异丙酚组相比,七氟醚组患者体外循环后心脏指数升高,术后心肌肌钙蛋白Ⅰ水平和心肌缺血发生率降低,ICU停留时间和住院时间缩短(P<0.05).结论 冠状动脉旁路移植术患者七氟醚的心肌保护作用优于异丙酚.     

Prognostic importance of automated ST-segment monitoring after coronary artery bypass graft surgery

Background : Automated ST-segment monitors are widely used in cardiac surgery units. The purpose of this study was to determine if cardiac morbidity and mortality, after CABG surgery, are predicted by ECG ST-segment changes on automated monitors.
Method : One hundred patients, who underwent CABG, were included in this prospective study. ST-segment deviations were recorded by an automated ST monitor, in the ICU, for 24 h after surgery. A reversible ST depression of more than 0.1 mV or a ST elevation of more than 0.2 mV and for at least 1 min were considered as significant episodes. Adverse cardiac outcomes were defined as: myocardial infarction (MI), severe left ventricular failure, ventricular fibrillation (VF) and cardiac-related death.
Results : Sixty patients (group 1) presented significant episodes of ST deviation (6δ5 episodes per patient). Forty patients (group 2) were free from ST changes. Eight patients from group 1 had postoperative adverse cardiac outcomes: 5 MI, 2 VF and 1 cardiac-related death. Patients from group 2 were all free from adverse cardiac outcomes. Automated ST-segment analysis during the first 24 h had a positive predictive value of 13% and a negative predictive value of 100%.
Conclusion : Automated ST analysis is a non-invasive, sensitive and very easy-to-use monitoring system to screen patients who may develop myocardial ischemia and cardiac complications after CABG surgery.     

On- and off-pump coronary surgery and perioperative myocardial infarction: an issue between incomplete and extensive revascularization.

OBJECTIVE: Complete myocardial revascularization is the standard for coronary artery bypass grafting. It has been shown, however, that off-pump coronary bypass surgery (OPCAB) may reduce completeness of revascularization without affecting perioperative myocardial infarction rates. We evaluated the influence of OPCAB on major postoperative events in a large consecutive cohort of patients, with special emphasis on risk factors for perioperative myocardial infarction. METHODS: From 1995 to 2004, 5935 patients underwent isolated coronary bypass surgery; of these, 4623 (77.9%) and 1312 (22.1%) underwent on-pump coronary surgery (CABG) and OPCAB, respectively. Patients undergoing OPCAB were matched to patients undergoing CABG by propensity score; logistic regression analysis models were used to study predictors of perioperative myocardial infarction. RESULTS: In matched pairs, postoperative mortality, myocardial infarction, stroke, and atrial fibrillation were similar between groups, while reoperation for bleeding, time on ventilator and red blood cell use were lower in patients undergoing OPCAB. The number of distal anastomoses was lower in patients undergoing OPCAB (2.2+/-0.80 in OPCAB vs 2.9+/-0.86 in CABG, p<0.001), as well as complete revascularization rates (61.9% in OPCAB vs 90.0% in CABG, p<0.001). Multivariate analyses, performed on preoperative and intraoperative variables, showed that both incomplete revascularization and increasing numbers of distal anastomoses (even when controlling for completeness of revascularization) were significant predictors of perioperative myocardial infarction, while CABG/OPCAB strategy did not influence it. CONCLUSIONS: The choice of surgical technique did not influence the occurrence of major perioperative complications and of myocardial infarction, which is negatively affected by incomplete or too extensive revascularization strategies.     

Concordance of electrocardiographic and scintigraphic criteria of myocardial injury after cardiac surgery.

The concordance of transmural electrocardiographic (ECG) changes and myocardial infarct imaging in detecting myocardial injury in the perioperative period was evaluated in 50 patients undergoing coronary artery bypass surgery and in 6 patients without coronary artery disease undergoing valve replacement. Scintigraphy with technetium-99m (Sn) labeled pyrophosphate was performed 3 to 7 days after surgery. Plasma creatine phosphokinase (CPK) levels were determined preoperatively and daily for 7 days postoperatively. Plasma MB-CPK was assayed fluorometrically in samples obtained at 12 hour intervals for 36 hours. Total CPK and MB-CPK concentrations were normal in all patients preoperatively but increased in every patient postoperatively. A total of 8 patients (16%) had evidence of perioperative infarction. Six of these patients (12%) with coronary artery disease exhibited abnormal images after bypass surgery, associated with transmural ECG changes in each case. The other 2 patients (4%) with coronary artery disease who had abnormal images were among 4 patients who developed bundle branch block after the operation. Abnormal images did not occur in any patient undergoing valve replacement despite total CPK and MB-CPK elevations. These results indicate that total CPK and MB-CPK elevations occur consistently after cardiac surgery and cannot be relied upon for detection of transmural infarction. Furthermore, new conduction defects may not necessarily be a sign of perioperative infarction, and infarct imaging may be a useful means of establishing myocardial infarction in this group of patients.